374 Borehole temperatures in permafrost are generally warming everywhere around the northern latitudes, but to varying degrees as a function of depth and location. In Alaska it has warmed as much as +3°C since the 1980s, but a more typical range is 0.5°-2°C. For a summary of observed permafrost temperature changes, see Table 6.8 and associated discussion on pp. 210-213,
375 The presence of permafrost helps to hold water near the land surface. L. C. Smith, Y. Sheng, G. M. MacDonald, L. D. Hinzman, “Disappearing Arctic Lakes,”
376 North of 45° N latitude, the single most important determinant of northern lake abundance is glaciation history, followed by the presence or absence of permafrost. On average, glaciated landscapes contain about four times as many lakes as nonglaciated landscapes; permafrost roughly doubles lake numbers. From GIS analysis of northern hemisphere lake distribution, I estimate that in a “permafrost-free” world, the number of known, mapped lakes north of 45° N latitude would be reduced from roughly 192,000 to 103,000 (-46%) and their total inundation area reduced from about 560,000 to 325,000 km2 (-42%). However, that is an extreme scenario. More realistic for 2050 is an overall reduction of known lakes to 155,000 (-15%) and 476,000 km2 (- 15%), respectively. These numbers are underestimates because the true number of Arctic lakes (i.e., unmapped) is in the millions. L. C. Smith, Y. Sheng, G. M. MacDonald, “A First Pan-Arctic Assessment of the Influence of Glaciation, Permafrost, Topography and Peatlands on Northern Lake Distribution,”
377 So-called “continuous” permafrost will decline even more, by 19%-53%. 2050 forecasts from the CGCM2, ECHAM4/OPYC3, GFDL-R30, HadCM3, and CSM climate models,
378 The percentage of dangerous buildings in large villages and cities ranges from 22% in Tiksi to 80% in Vorkuta, including 55% in Magadan, 60% in Chita, 35% in Dudinka, 10% in Noril’sk, 50% in Pevek, 50% in Amderma, and 35% in Dikson. On the Baikal-Amur Mainline railroad 10%-16% of the subgrade in permafrost was deformed by permafrost in the early 1990s, rising to 46% by 1998.
379 This map is assembled from several types of data. The permafrost load-bearing capacity model (gray tones) is very new and will comprise the Ph.D. dissertation of D. Streletskiy, University of Delaware. Permafrost is warmed by rising air temperatures and/or deeper winter snowpack (deeper snow insulates the ground). In general, warmer permafrost means lower load-bearing capacity, but other factors like geology, ice content, and thermal properties are also important. These processes have recently been incorporated into Streletskiy’s semiempirical model, driven here by NCAR CCSM3 projections of surface temperature and snow depth averaged over fifteen-year periods, 2000-2014 and 2045-2059, assuming an SRES A1B emissions scenario. The map shows the projected changes occurring between those two time intervals. “Severe loss” is strength loss of >50%, “moderate” is 25- 50%, and “mild” is under 25%. The hatched markings refer to increased travel cost from reduced winter road suitability, work done at UCLA by my graduate student Scott Stephenson. Winter roads may only be used for transport where climate provides suitable conditions for their construction and use. Winter road suitability is strongly correlated with freezing index, which is a function of temperature. Land area was classified as suitable for winter road use where mean temperature was 0°C or lower and snow depth exceeded 20 cm. Rivers and lakes were classified as suitable if they received at least 23 cm of freeze depth. Suitability losses were cumulated from November to March. Again, NCAR CCSM3 projections of surface temperature were averaged over fifteen-year periods 2000-2014 and 2045-2059 assuming a SRES A1B emissions scenario, with the map showing the projected change in areal extent of suitability occurring between those two time intervals. Note that this map does not require that winter roads are currently being used in these areas, but instead measures the climatic suitability for their potential use.
380 Personal interview with D. Augur, assistant deputy minister, NWT Department of Transportation, Yellowknife, July 9, 2007. On average, permanent roads cost $0.5-$1.0 M/km to build, whereas winter roads average $1,300 M/km.
381 The Tibbitt-Contwoyto is jammed with heavy trucks during its brief operating season. In 2007 it absorbed eleven thousand loaded trips in just seventy-two days. D. Hayley and S. Proskin, “Managing the Safety of Ice Covers Used for Transportation in an Environment of Climate Warming,” 4th Canadian Conference on Geohazards, May 20- 24, 2008, Quebec City, Canada.
382 Geologically speaking, a kimberlite pipe. Diamonds form under extreme pressure deep in the Earth’s crust but can sometimes be found in kimberlite pipes, narrow chimneys of igneous rock that can reach the surface. In the NWT kimberlites are often found under lakes because they are softer than the surrounding granitic rocks, thus becoming eroded depressions that fill with water.
383 Personal interview with Tom Hoefer, manager of external and internal affairs, Diavik Diamond Mines, Inc., Yellowknife, NWT, July 9, 2007.
384 Personal interview with Divisional Forester Jeremy Beal, Tolko Industries Ltd., High Level, Alberta, June 4, 2007.
385 Compared with other types of road, properly constructed and used winter roads have surprisingly low impact on the environment, especially over lakes and wetlands. See S. Guyer, B. Keating, “The Impact of Ice Roads and Ice Pads on Tundra Ecosystems,” National Petroleum Reserve-Alaska, U.S. Bureau of Land Management, BLM- Alaska Open File Report 98 (April 2005), 57 pp.
386 L. D. Hinzman et al., “Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions,”
387 One of the ways to mitigate the climate-warming effect is to deploy sweepers to clear snow from the planned roadway, reducing its insulating effect on the ground.
388 A $270 million proposal is pending to build a port road from Bathurst Inlet, which would help the diamond mines to offset decline of the Tibbitt-Contwoyto ice road as well as enabling other mining activity in the area. G. Quenneville, “Bathurst Inlet Project Reconsidered,” Northern News Services, June 15, 2009.
389 Obviously, in terms of sheer numbers, most of the U.S. increase will be in southern states. However, the United States as a whole is still a NORC country and the +15 million figure for its northern states is probably conservative. Alaska today has fewer than a million people, for example, but is one of the fastest-growing U.S. states, projected to grow nearly 40% by 2030. In contrast, New York is projected to grow less than 3%. U.S. Census Bureau, Population Division, Interim State Population Projections, 2005, www.census.gov/population/www/projections/projectionsagesex.html. Table data are from United Nations Population Division: The 2008 Revision Population Database (medium variant), http://esa.un.org/u/npp (accessed July 26, 2009).
390 This calculation is from GIS analysis for land area of the northern quarter of the planet, i.e., between 45° and 90° N latitude. About twenty-one million square kilometers is underlain by some form of permafrost, and eighteen million were glaciated in the last ice age, leaving a smoothed landscape (except in mountain belts) that is relatively easy to get around on. Adding in all the coastal and low-lying areas (here assumed simply as land elevations three hundred meters a.s.l. or less), because they are warmer and more accessible than high-elevation terrain, yields about twenty-seven million square kilometers, of which thirteen million is currently in some stage of permafrost. Subtracting the permafrost areas leaves roughly fourteen million square kilometers of ostensibly livable land.
391 Unlike North America and northern Europe, Eurasia was not extensively ice covered during the last ice age. Most of modern-day Russia has been occupied by humans for at least the past forty to forty-five thousand years and perhaps longer. Even in the high Arctic, new archaeological discoveries at Mamontovaya Kurya and the Yana River indicate human activities thirty to forty thousand years old. See Pavel Pavlov et al.,
392 They are loaded with ancient gene haplogroup U, especially U5B1B1, the so-called “Sami motif,” dating back fifty-five thousand years to the Iberian Peninsula, from where they migrated north at the end of the ice age. T. Lappalainen et al., “Migration Waves to the Baltic Sea Region,”
393 Country-averaged population densities for Canada, China, and India are 3,141, and 369 persons per square kilometer, respectively, equivalent to 82.4, 1.75, and 0.67 acres of land per person.
